palmer



L. E. PALMER ESCAPEMENT MECHANISM FOR TYPEWRITER March 31, 1964 Filed 0017, 1961 3 Sheets-Sheet 1 |NVENT0R.

LEON E. PALMER (A E, SLMM-k ATTORNEY.

March 31, 1964 E. PALMER 3,126,993

ESCAPEMENT MECHANISM FOR TYPEWRITER Filed Oct. 17.: 1961 3 Sheets-Sheet2 March 31, 1964 E. PALMER ESCAPEMEN'T MECHANISM FOR TYPEWRITER 3Sheets-Sheet 3 Filed Oct. 17, 1961 FIG. 4

United States Patent 3,126,998 ECAPEMENT MECHANlSM FQR TYPEWRITER LeonE. Palmer, Lexington, Ky., assignor to International Business MachinesCorporation, New York, N.Y., a corporation of New York Filed Oct. 17,1961, Ser. No. 145,706 7 Claims. (Cl. 197-492) This invention relates totypewriters and more particularly to escapement mechanisms having aninherent time delay action especially Well suited for use withtypewriter space bars.

In typewriters employing a single element type head like that shown inUS. Patent 2,919,002, issue to L. E. Palmer on December 29, 1959, acertain lapse of time occurs after aletter key is struck by the typistand before escapement takes place, such a time period normally being inthe order of about 40-50 milliseconds. The letter. key cycle entails apositioning of the head and a typing of a character before escapementcan take place. With respect to the space bar cycle, however, escapementnormally takes-place within a time lapse of about 20-30 millisecondssince there is no need for delay. Due to the substantialdifierencebetween these two periods of time, it is found that without correctivemeasures being present it is possible for the typist to strike the spacebar too soon following the striking of a letter key with the result thatthe escapement mechanism will receive impulses from two actuatingsources and only one escapement will occur. In such an event theintended space between consecutive words will be lost despite theactuation of the space bar. It has been discovered that thisdisadvantage may be overcome by storing the impulse from the space baruntil after the escapement action from the letter key is completed, andthereupon passing the space bar impulse to the escapement mechanism,whereupon the intended sequential operations of that mechanism areobtained.

An object of the invention is to provide an improved escapementmechanism for typewriters.

Another object is to provide an improved mechanism which operates tointroduce a delay in the operation of an escapement mechanism resultingfrom actuation of a typewriter space bar until a printcycle which maythen be taking place, has been completed.

A further objectis to provide an improved arrangement for storing anescapement impulse from a typewriter space bar when the escapementmechanism is opering in response to actuation of a type key.

Other objects of the invention will be pointed out in the followingdescription and claims and illustrated in the accompanying drawings,which disclose by way of example, the principle of the invention and thebest mode, which has been contemplated, of applying that principle.

In the drawings:

FIG. 1 is a plan view, with portions broken away, of a carriage for atype member and means for efiecting its escapement.

FIG. 2 is a cross sectional view of a keyboard having the improved.space bar escapement drive mechanism associated therewith.

FIG. 3 is a perspective view of an actuating means for an escapementmechanism associated with the carriage for the type head.

FIG. 4 is a perspective, View of a mechanism controlling operation -.ofthe escapement mechanism.

FIG. 5 is an elevational view of a clutch as viewed from the sideopposite that shown in FIG. 2.

The improved escapement mechanism disclosed herein forms-part of atypewriter which is similar to that shown and described in the patentmentioned above. The typewriter includes the usual frame having a baseand side members-1% and 11- mountinga keyboard having key levers, notshown, which may be actuated to effect operation of a single elementprint head 12, shown in outline in FIG. 1, for printing characterscorresponding to the levers actuated. The mechanisms for driving thehead have not been shown since they form no part or" the presentinvention. Print head 12 is mounted upon a carriage 13, which isslidably supported by a stationary bar 14 extending transversely of thetypewriter. Connected to one side of the carriage is a flexible cable 15which passes around pulleys l6 and 1'7 attached to the side frame 1%,and then is wrapped around a pulley i8 fixed to a shaft 19.

Another cable 2A) is connected to the carriage and passes around apulley 21 attached to the side frame ii. at the opposite side of themachine. Cable Ztl is then wrapped around a pulley 22 which is alsofixed to the shaft 19. A spring motor 23 is connected to the shaft 19and tends to rotate the latter in a direction to wind up cable 26 whilepaying out cable 15. It will be seen that this effects movement of thecarriage 13 from left to right in a typing direction aiong the bar 14when the escapement mechanism, later to be described, is suitablyactuated. Pivotally mounted on the carriage is a dog 24 which is urgedby a spring 25 into engagement with teeth 26 on the bar 14 for holdingthe carriage against movement by the motor 23 acting on the cables 15and 20. When the dog 24 is moved out of engagement with one of the teeth26 and then immediately released, the carriage 13 moves to the rightuntil the dog engages the next adjacent tooth. This results in amovement of the print head 12 to its next printing position.

For moving the dog away from the teeth 26 there is provided a bail 3h,FlGS.. 1 and 3, which is pivotally supported at its ends in the sideframes it) and ll and is tiltable between a normal first position inwhich the dog engages with a tooth on the bar 14 and a tilted secondposition in which the dog is disengaged from that bar. Formed on the dogis a projecting portiotn 31 loosely hooking over the top edge of thebail so that a rocl ing of the latter to its second position results ina pivoting of the dog away from the teeth 26.

Adjacent the right end of the bail, and as best shown in the perspectiveview of FIG. 3, is a framework forming a portion of the escapementmechanism and including a hook member 32 having a lip releasablyengageable with the top edge of a plate 32 a fixed to the bail andserving to tilt the bail to its second position against the action of arestoring spring 33, whenever that framework itself is pivoted in onedirection, as later to be explained. It will be understood that theframework includes structure employed to effect escapement actionfollowing the striking of a letter key, as well as escapement actioncomprehended by the present invention. For purposes of the presentdisclosure, the framework is shown as being pivotable about a rod theaxis of which is generally parallel to the tilting axis of the bail.Journalled upon this rod is a U-shaped member having a shelf 35projecting into the space between its side arms 36 and 37, and with abiasing spring 38 attached thereto for holding the U-shaped member in anupward position. An arm 39, later to be described, is pivotally attachedto the U-shaped member between the side arms. Underlying the shelf 35 isa second shelf 45) formed integral with another arm 41 pivotally mountedon rod 34, and by means of an adjustable spacing screw 42 carried by theupper shelf Si downward movement of arm 39 causes a downward movement ofarm 4?. when the screw engages the lower shelf dtl. The arm 41 isprovided with a slot #3 receiving one end of a link 44 employed in theconventional escapement action following the striking of a letter key.As will thus be apparent, the actuation of the letter-key-link 44 maythus cause an escapement of 2.9 the carriage independently of anyactuation by the spacebar-actuated means, and, due to the lost motion oflink 2-4- in the slot 43, the framework may pivot downwardly to effectan escapement caused by the space-bar-actuated means independently ofany actuation by the letter-keyactuated means.

The arm 41 is integrally connected to a spaced arm 45 which also ispivotally journalled on rod 34 and which at an intermediate locationcarries a pivot pin 46. The hook member 32 is pivotally mounted on pin46 and by means of a tension spring 47 connected between the lower endof the hook member and the outer end of arm 45, the bail-engaging lip ofthe hook member is urged into bail-engaging position. For effecting arapid release of the bail from the hook member, that book member isprovided with a cam projection 48 which moves against a stationary pin49 attached to the typewriter frame and causes a rapid lifting of thelip of the hook member as the framework is pivoted to its downwardposition.

Referring now to FIGS. 2 and 4, a rotatable first shaft 50 which turns180 in response to the striking of a letter key, and a constantlyrotating second shaft 51, each of the shafts serving the respectivepurposes described in the aforementioned Palmer patent, are present inthe typewriter with which the present invention is employed. Shaft 50functions as a cyclically operable means and has rigidly attachedthereto a fluted portion 52 serving in the positioning of the type head12, as well as an escapement cam portion 53 having a pair of spaced camlobes 53a and 5311 serving to actuate the escapement link 44 when aletter key is actuated. As shown in FIG. 2, a lever 54 is rocked by oneor the other of the cam lobes to actuate the link 4 after a character istyped. As a feature of the present invention, an open space is formedbetween the portions 52 and 53 on the shaft and an axially projectingcam lobe 530 extends into that space. Within that space a cylindricalshuttle member 55 encompassing the shaft 50 and reciprocable therealongis mounted, a compression spring 56 being interposed between the shuttlemember and the fluted portion 52 of the shaft. The shuttle member,moreover, is provided with an axially projecting cam lobe 57 which whencontacted by a cam lobe 530, in one home position of shaft 50 as shownin FIG. 4, holds the shuttle member to the left in its retractedposition against the action of spring 56, all for a purpose later tobecome apparent. As the shaft 50 turns 180 during the typing of acharacter, the shuttle member moves first to the right in FIG. 4 andthen is returned to the position shown by a second cam lobe 53cdiametrically opposite to that shown.

Rigidly attached to the shuttle member 55 is an abutment 58, and bymeans of a slot in the shuttle member and into which a flat plate 59projects at all times, rotation of the shuttle member is preventedwithout interference with its reciprocable movement on shaft 50.

Considering now FIG. 2, a space-bar-actuated means or linkage, includesa space-bar 60 adapted upon being struck to move downwardly against theaction of a restoring leaf spring 61. Pivotally attached to this bar isa lever 62 supported upon a rod 63 and with the distal end of the leverbeing engageable with one end of a bell crank 64 which in turn issupported upon and rotatable about a rod 65. The other end of the bellcrank is pivotally attached to a pawl 66 which is biased by spring 67acting upon the linkage in opposition to spring 61, the pawl beingguided in its movement by means of a bifurcated guide 68 whichconveniently may be mounted upon a stationary wall 69 the lower edge ofwhich serves to latch the interposer now to be described.

This interposer may comprise an elongated narrow member 70 guided in abifurcated guide 71, and resting upon the end of an adjustable screw orthe like 72 mounted in a base portion 73 of the typewriter frame. At itsend confronting the above described linkage, the interposer has acontact surface '74 adapted to be contacted by a shoulder 75 on the pawl66 (FIG. 4) and to receive therefrom an impulse moving that end of theinterposer downwardly and rearwardly into unlatched position when thebar 60 is depressed. Extending upwardly from the interposer is aprojection 76, and mounted upon the interposer and biased into normallatching position by means of a spring 77 is a latch member 78. A spring00 normally urges the interposer rearwardly and holds a nose 81 of theinterposer in contact with the arm 39 of the framework, this contactbeing further assisted by a tension spring 82 joining the interposer andarm 39, as best seen in FIG. 2.

Adjacent its rearward end, the interposer includes a first shoulder 83adapted during the unlatched rearward movement of the interposer tocontact one arm 84 of a bell crank pivoted upon a rod 85, the other arm86 of that bell crank having an edge serving as a dog for a clutchmember 37. Also adjacent its rearward end, the interposer includes asecond shoulder 88 adapted to be contacted by a drive pin 89 projectinglaterally from an arm of a restoring lever 90, later to be described.

The constantly rotating shaft 51 carries a ratchet wheel having teeth91, and journalled upon that shaft is a cam member 92. Rigidly attachedto one face of the cam 92, as seen in FIG. 5, is a plate 93 havingrecesses 94 and 95 therein and into which a dog 96 is adapted to engagewith a ratchet-like action to prevent reverse rotation of the cam. Thedog 96 is mounted upon a pin 97 and is provided with an angularly spacedarm integral with the dog 96 and mounting a tension spring 98, the otherend of which is attached to the arm 86. Mounted between the other faceof cam 92 and the ratchet wheel, is the clutch member 87 havingprojecting portions 99 and 100 into the path of which the dog 86 isurged under the action of spring 98. A pin 101 extending from the sideof the cam through an elongated slot 101a in the cluch member mounts atension spring 102 which is connected to an arcuate arm 103 pivoted uponanother pin 104 extending from the cam through another slot 104a. Thisarm carries a tooth 105 which is engageable with one of the teeth 91 onthe ratchet wheel when spring 102 is free to contract. The end of theslot 104a adjacent the free end of the arm 103 acts as a cam surfaceagainst which a pin 106 on the free end of the arm slides when theclutch member 87 and the cam 92 turn relative to each other. When thedog 86 is moved out of the path of the projecting portion 99, the pin106 acting against the cam surface under the action of the spring 102causes the clutch member to rotate counterclockwise relative to the cam92 until the tooth 105 engages one of the teeth 91. This results in adriving of the cam 92 by the shaft 51 until the dog 86 again engages oneof the projections and holds the clutch member while the cam 90continues to turn until the arm 103 is forced outwardly by the pin 106acting on the cam surface. As will thus be noted, the clutch arrangementimmediately engages the arm 103 mounted on the cam 92 with the teeth 91and causes the cam to rotate as soon as dog 86 is pulled from itslocking engagement with the clutch member during the rearward movementof the interposer 70. This cam rotation continues until the dog 86 isre-engaged with the next projection on the clutch member, after whichthe tooth 105 is lifted out of engagement with the teeth 91 and the camremains at rest until the dog 86 again is actuated.

Bearing against the edge of cam 92 at all times is a cam follower 110pivotally mounted upon an arm 111 which in turn is pivoted upon the rod85. This arm includes a cam surface 112 against which a cam follower 113mounted upon one arm 114 of a framework-actuating bell crank is located.The other arm 115 of this bell crank, which also is pivoted upon rod 85,is provided with a laterally extending shoulder 116 positioned above ashort rearwardly bent portion 117 at the lower end of the arm 39 of theframework. Thus, as the arm 115 rocks downwardly, as seen in FIG. 2, theportion 117 which is lodged under shoulder 116, due to previous movementof the unlatched interposer to the rear, will be forced downwardly bythat shoulder 116 and the framework will be pivoted to cause the hookmember 32 to actuate the bail. During this same downward movement of arm115, the lower edge of that arm strikes a laterally projecting shoulder118 on the interposer-restoring lever 90 which is separately andpivotally mounted alongside the arm 115 upon a suitable pin 119. Theresultant pivoting of lever 90 causes its pin 89 to move against theshoulder 88 of the interposer and to drive that interposer to the leftinto its latched position. As the arm 115 moves downwardly with thelower end of the arm 39 under the shoulder 116, the left side of the arm39 moves in back of an upwardly projecting plate 120 which holds the arm39 engaged with the shoulder 116 while the interposer 70 is being forcedto the left. After the interposer has been moved to its latched positionand the arm 115 has been moved upwardly to a position in which the arm39 clears the plate 120, the spring 82 operates to move the arm 39 fromunder the shoulder 116 and into engagement with the nose 81 on theinterposer.

With the foregoing description in mind, reference now is made to FIG. 4wherein it will be seen that the abutment 58 moves into and out of thepath of movement of projection 76 on the interposer depending upon theangular position of shaft 50. The motion of this shaft with its cam 53which serves to actaute the link 44 for effecting escapement necessarilyinvolves a predetermined period of time. It will further be noted thatfollowing the unlatching of the interposer from the wall 69 during aprint cycle, the interposer may initially move to the rear only untilthe projection 76 comes into contact with the abutment 58 and that thisamount of movement is insufficient to cause the shoulder 83 of theinterposer to trip the dog 86 of the clutch (FIG. 2). The rotation ofshaft 5t) brings the cam lobes 53a and 53b alternately into position foreffecting the actuation of the letter-keyactuated means, such as link44. Significantly, this same rotation causes the cam lobe 530 to movefrom its home position in contact with the cam lobe 57 on the shuttle55, causing the abutment 58 to move into obstructing position withrespect to the projection 76 on the interposer 70 at the same time theescapement mechanism is receiving its impulse from theletter-key-actuated means. As soon as the printing and escapementresulting from actuation of a letter key has been completed, theabutment 58 is moved out of the path of the projection 76 and theinterposer 70 continues its movement to elfect escapement for theearlier actuated space bar.

It will also be appreciated that shaft 50 is in a position like thatshown in FIG. 4 at the time the interposer 70 is restored to its latchedposition so that abutment 58 provides no obstruction to projection 76during that restoring movement.

If no character print cycle is taking place when the space bar 69 isdepressed, the interposer 70 is free to move immediately for effectingan escapement.

While there has been shown in this application one form which theinvention may assume in practice, it will be understood that it may bemodified and embodied in other forms without departing from the scope ofthe invention.

What is claimed is:

1. In a typewriter, a movable carriage having a single element type headthereon, an escapement mechanism for said carriage, cyclically operablemeans for effecting a printing operation by said type head, means drivenby said cyclically operable means for actuating said escapementmechanism, space-bar-operated means for actuating said escapementmechanism independently of said driven means, and means positioned bysaid cyclically operable means during a cycle of printing operation forobstructing movement of said space-bar-operated means until the cycle ofprinting operation has been completed.

2. In atypewriter, a movable carriage having a single element type headthereon, anescapement mechanism for said-carriage, cyclically operablemeans for effecting a printing operation by said type head and includinga rotatable shaft, means driven by said shaft for actuating saidescapement mechanism following a printing operation, space-bar-operatedmeans for actuating said escapement mechanism independently of saiddriven means and including a longitudinally movable interposer, and aretractable means movable during each cycle of printing operation intothe path of interposer movement thereby to obstruct movement of saidinterposer and to prevent operation of said escapement mechanism by saidinterposer until completion of said cycle of printing operation, saidretractable means being movable by said shaft into retracted positionout of the path of movement of said interposer following completion ofeach cycle of printing operation.

3. A typewriter as defined in claim 2 including means for latching saidinterposer in a position of readiness for subsequent operation of saidspace-bar-actuated means following completion of an escapement of saidcarriage caused by a previous movement of said interposer.

4. In a typewriter, a movable carriage having a single element type headthereon, an escapement mechanism for said carriage, cyclically operablemeans for effecting a printing operation by said type head and includinga rotatable shaft having first and second cam members carried therebyand rotatable therewith, means driven by said first cam member foractuating said escapement mechanism following a printing operation,space-bar-operated means for actuating said escapement mechanismindependently of said driven means and including a longitudinallymovable interposer, and a retractable means movable during each cycle ofprinting operation into the path of interposer movement thereby toobstruct movement of said interposer and to prevent operation of saidescapement mechanism by said interposer until completion of said cycleof printing operation, said retractable means being moved by said secondcam into retracted position out of the path of movement of saidinterposer following completion of each cycle of printing operation.

5. A typewriter as defined in claim 4 wherein said retractable meanscomprises a shuttle member movable axially of and in surroundingrelation to said shaft and being restrained against rotation with saidshaft.

6. A typewriter as defined in claim 5 including a spring normally urgingsaid shuttle member toward obstructing position within the path ofmovement of said interposer.

7. In a typewriter having a single element type head mounted upon amovable carriage, the combination comprising, an elongated tiltablebail, a stationary bar having teeth thereon extending along the path ofmovement of said carriage, teeth-engaging means mounted upon saidcarriage and biased toward teeth-engaging position, said teeth-engagingmeans being connected to said bail for movement lengthwise of the sameand for actuation into and out of teeth-engaging position in dependenceupon the degree of tilt of said bail, an escapement mechanism having aframework pivotable about an axis generally parallel to the axis oftilting of said bail; said framework having an actuating arm, a hookmember releasably engageable with said bail for moving the same to itstilted position during pivoting of said framework in one direction, andmeans for moving said hook member normally into engagement with saidbail during pivoting of said framework in its other direction; a movablespace-barlinkage; an elongated reciprocable interposer normally retainedin latched position against a stationary portion of the typewriter frameand having a first portion engageable by said linkage for unlatching ofsaid interposer, a second portion engageable with said arm on saidframework, a latching means, and a rigid projection extending from saidinterposer; cyclically operable means for effect ing a printingoperation by said type head and including a rotatable first shaft, aretractable abutment means movable during each cycle of printingoperation into the path of movement of said projection, said abutmentmeans being movable by said first shaft into retracted position out ofthe path of movement of said projection following completion of eachcycle of printing operation, means normally urging said interposertoward said framework, the relative locations of said projection and ofsaid abutment in their intersecting paths of movement providingsufiicient space for unlatching of said interposer and for holding theprojection of the unlatched interposer in contact with said abutmentduring a portion of the time of rotation of said first shaft thereby tocause a time lag in the movement of said bail to its tilted position, arotatable second shaft having a clutch carried thereby in normallydisengaged relation thereto and including a cam, means operable by saidinterposer following movement of said abutment out of the path of saidprojection for temporarily engaging said clutch with said second shaft,and means operable by said cam, while said clutch is engaged with saidsecond shaft, for engaging said actuating arm of said framework to pivotsaid framework in said one direction and for striking said interposerthereby to restore said interposer to its latched position.

Gumprecht Aug. 23, 1921 Barney Nov. 3, 1925

1. IN A TYPEWRITER, A MOVABLE CARRIAGE HAVING A SINGLE ELEMENT TYPE HEAD THEREON, AN ESCAPEMENT MECHANISM FOR SAID CARRIAGE CYLICALLY OPERABLE MEANS FOR EFFECTING A PRINTING OPERATION BY SAID TYPE HEAD, MEANS DRIVEN BY SAID CYCLICALLY OPERABLE MEANS FOR ACTUATING SAID ESCAPEMENT MECHANISM, SPACE-BAR-OPERATED MEANS FOR ACTUATING SAID ESCAPEMENT MECHANISM INDEPENDENTLY OF SAID DRIVEN MEANS, AND MEANS POSITIONED BY SAID CYCLICALLY OPERABLE MEANS DURING A CYCLE OF PRINTING OPERATION FOR OBSTRUCT- 